1. Field of the Invention
This invention relates to an optical fiber cable cover removing device which removes the covering layer of an optical fiber cable.
2. Description of Related Art
Conventionally, an optical fiber has been cut at a predetermined position for use so that the optical fiber can be abutted and joined to other optical fiber and devices. In the case in which the optical fiber is cut, the covering layer must be removed in order to expose a bare fiber. In order to remove the covering layer of an optical fiber, an optical fiber cable covering removing device which removes the cable covering layer of the optical fiber in one operation is used frequently.
FIGS. 8 and 9 are exploded views showing an example of conventional optical fiber cable covering removing device. An optical fiber cable covering removing device in this example comprises a support member 2 and a fiber holder retainer 3.
The support member 2 comprises a main body 6 having a pair of freely opening and closing cutter holders 4 and 5 attached together by hinge, and a lid 7. One cutter holder 4 comprises a first cable covering removing cutter 8 which removes the cable covering layer of the optical fiber, and a tip retaining section 10a which retains the tip of the optical fiber 20. The other cutter holder 5 comprises a second cable covering removing cutter 9 and a tip retaining section 10b on which a guide groove 11 which retains the tip of the optical fiber 20 is formed. Also, in the guide groove 11 of the tip retaining sections 10a and 10b, a heating plate (not shown in the drawing) and a heating device (not shown in the drawing) are embedded. The heating device heats the covering layer of the optical fiber 20 positioned by means of the guide groove 11 of the tip retaining section 10a and 10b via the heating plate, to a temperature at which temperature the cable cover does not melt. Here, the optical fiber 20 is made of a bare fiber 20a and a covering layer which is formed around the bare fiber 20a. 
A fiber holder retainer 3 comprises a retainer upper member 12 and a retainer lower member 13 attached together by a hinge so as to be openable and closeable. On the retainer lower member 13, a base stand 15 and a fiber holder 14 having two opening and closing plate members 16 and 16 attached together by a hinge so as to be openable and closeable are fit against the upper surface 15a of this base stand 15.
Also, the support member 2 and the fiber holder retainer 3 are connected via fitting holes 17 and 17 and guide bars 18 and 18. On both longitudinal sides of the retainer lower member 13, the fitting holes 17 and 17 are formed in parallel with the longitudinal direction. The fitting holes 17 and 17 lead to fitting holes (not shown in the drawing) formed on both sides of the longitudinal direction of a main body 6 of the support member 2. Also, the fitting holes 17 and 17 lead to the fitting holes of the main body 6, and then the guide bars 18 and 18 extending from this fitting hole are inserted in the fitting holes 17 and 17. Also, the guide bars 18 and 18 are fitted to the fitting holes 17 and 17, in such a way that the fiber holder retainer 3 can be moved by external force such as manual manipulation by an operator, and the positioning can be fixed when external force stops. In the removal of the covering layer of the optical fiber 20 in which the optical fiber cable cover removing device of this example is used, first, the optical fiber 20 is mounted on the base stand 15 in condition that the opening and closing members 16 and 16 of the fiber holder 14 are opened against the base stand 15, and then the optical fiber 20 is retained by the fiber holder 14 by closing the opening and closing member 16 and 16 and the retainer upper member 12.
Next, the optical fiber 20 is mounted in the guide groove 11 of the tip retaining section 10b of the cutter holder 5, the optical fiber 20 is retained by closing the cutter holder 4 and by fitting the tip retaining section 10a to the tip retaining section 10b. 
Here, the optical fiber 20 positioned by the guide groove 11 is heated to the temperature at which the optical fiber 20 does not melt by the heating device via the heating plate, and then the covering layer is softened.
Next, the support member 2 and the fiber holder retainer 3 are clamped, and then the optical fiber 20 is positioned by the tip retaining section 10a of the cutter holder 4, the tip retaining section 10b of the cutter holder 5, and the guide groove 11 on the tip retaining section 10b. In this condition, only the covering layer of the optical fiber 20 is incised by the first cable covering removing cutter 8 and the second cable covering removing cutter 9.
Next, while maintaining the support member 2 and the fiber holder retainer 3 clamped, the fiber holder retainer with the fiber holder 14 are moved away from the support member 2 along the guide bars 18 and 18 until the end of the optical fiber 20 moves away from first cable covering removing cutter 8 and the second cable covering removing cutter 9. Then, because the movement of the covering layer between the tip and the incising position is limited by the first cable covering removing cutter 8 and the second cable covering removing cutter 9, the covering layer is cut at the incising position, and the bare fiber 20a is extracted from the covering layer, and thus the covering layer is removed as a result.
As explained above, in such an optical fiber cable covering removing device, the removing operation of the covering layer must be performed while the support member 2 and the fiber holder retainer 3 are clamped.
In such an optical fiber cable covering removing device, there was a problem that when extracting the optical fiber 20 through the first cable covering removing cutter 8 and the second cable covering removing cutter 9, the seizing force on the optical fiber by these cable covering removing cutters was insufficient, and thus the removal of the covering layer was insufficient.
Also, there was a problem in that when extracting the optical fiber 20 through the first cable covering removing cutter 8 and the second cable covering removing cutter 9, the clamping force on the fiber holder retainer 3 was insufficient, and thus the optical fiber 20 could not be extracted from the support member 2 due to the slipping in the fiber holder 14.
Particularly, in the case in which the optical fiber is a multiple type of optical fiber tape, and in the case in which a number of the optical fibers is increased, and in the case in which the clamping force exerted by an operator is weak, such problems tend to occur.
The present invention was made in view of the above situation, and an object of present invention is to provide an optical fiber cable covering removing device which can remove the covering layer of an optical fiber reliably and safely.
The above problems can be solved by an optical fiber cable covering removing device having a support member having a pair of freely opening and closing cutter holders provided with cable covering removing cutters which remove the covering layer of the optical fiber and being provided with a cutter holder fixing structure which fixes the cutter holder in a closed position, a fiber holder which can freely open and close and retains the optical fiber, a fiber holder retainer which can move the fiber holder toward and away from the support member along longitudinal direction of the optical fiber.
The cutter holder fixing structure should preferably impart fixing force parallelly to the cable covering removing cutter provided on the cutter holder.
The fiber holder retainer should preferably be provided with a fiber holder fixing structure which fixes the fiber holder in the closed position.
The fiber holder fixing structure should preferably be disposed near the center of the fiber holder.
The optical fiber cable covering removing device of the present invention has a support member having a pair of freely opening and closing cutter holders having the cable covering removing cutters which remove the covering layer of the optical fiber, and the freely opening and closing fiber holder which retains the optical fiber. In the present invention, the fiber holder retainer which can move the fiber holder toward and away from the support member along longitudinal direction of the optical fiber is provided, and the support member is provided with the cutter holder fixing structure which fixes the cutter holder in the closed position. Therefore, the problem that the seizing force of the cable covering removing cutters to the optical fiber becomes weak, and the removal of the covering layer cannot be done sufficiently when removing the covering layer, does not occur. Also, an operator does not have to clamp the optical fiber cable covering removing device himself in the operation, even in the removing operation of the covering layer of the multiple type of optical fiber with many fibers, thus the removal of the covering layer can be done reliably and safely.
Also, because the cutter holder fixing structure can impart force uniformly in parallel to the cable covering removing cutters formed on the cutter holder, the seizing force on the optical fiber is sufficiently transmitted on the cable covering removing cutters, the removal of the covering layer of the optical fiber can be done satisfactorily.
Furthermore, because the fiber holder retainer is provided with the fiber holder fixing structure which fixes the fiber holder in the closed position, the seizing force on the optical fiber does not become insufficient, and therefore the optical fiber does not slip in the fiber holder, and the optical fiber is not pulled out from the fiber holder. Also, in the removing operation of the covering layer of the multiple type of optical fiber with many fibers, the removal of the covering layer can be performed reliably and safely. Because the fiber holder fixing structure is disposed near the center of the fiber holder, the optical fiber is firmly retained in the fiber holder.